Create mock for kolibri.resources that automocks every exported Resource class

[jonboiser]

This simplifies the mocking of kolibri.resources. Now, if your test might call some resource, do this:

jest.mock('kolibri.resources')

This will import a mock that automocks every Resource class. Then, if you need to mock a specific Resource, import it, set its mock behavior (and remember to reset it at the end of the test)

import { FacilityUserResource } from 'kolibri.resources';

jest.mock('kolibri.resources')

describe('', () => {
  afterEach(() => {
    FacilityUserResource.fetchCollection.mockReset();
   })
  it('...', () => {
	FacilityUserResource.fetchCollection.mockResolvedValue([...]);
   })
})

Since this mock should handle most use cases, I also deleted the jestMockResource utility.

[rtibbles]

Nice, good cleanup! Tests still pass, so looking good.